Object Required: res.toString(CryptoJS.enc.Hex) #1

Hi. This is a great wrapper, but it errors for me on this line:
Response.Write res.toString(CryptoJS.enc.Hex)
Error: Microsoft VBScript runtime error '800a01a8'

Object required: 'aa747c502a898200f9e4'

It seems to have problem with res.toString.
Any help appreciated.